Ammonium phosphate fertilizer diammonium

Ammonium phosphate fertilizers are relatively impure (purity ca. 85%), due to their being prepared with nonpurified wet-process acid. Commercial monoammonium phosphate contains 11 to 13% N and 48 to 53% P2O5 (theoretically 12.2% N, 61.7% P2O5). Commercial diammonium phosphate contains 16 to 18% N and 46 to 48% P2O5 (theoretically 21.2% N, 53.7% P2O,). 

In the period 1965-75, TSP sipplied approximately 15%r20% of the fertilizer phosphate used worldwide. This declined to 13.3% in 1988 and to 10.7% in 1992, primarily as a result of a continuous increase in the use of ammonium phosphates, mainly diammonium phosphate (DAP). 

The routes by which mineral phosphates are processed into finished fertilizers are outlined in Eigure 7. World and U.S. trends in the types of products produced are shown in Eigures 8 and 9, respectively. Most notable in both instances is the large, steady increase in the importance of monoammonium and diammonium phosphates as finished phosphate fertilizers at the expense of ordinary superphosphate, and to some extent at the expense of triple superphosphate. In the United States, about 65% of the total phosphate appHed is now in the form of granular ammonium phosphates, and additional amounts of ammonium phosphates are appHed as integral parts of granulated mixtures and fluid fertilizers. 

The ammonium phosphates took over the lead in 1967. Diammonium phosphate (DAP) is made from wet process phosphoric acid of about 40% P2O5 content and ammonia. The usual finishing NH3 H3P04 mole ratio is 1.85-1.94 1. Monoammonium phosphate (MAP) is made with a final NH3iH3P04 ratio of 1 1. Current production percentages for phosphate fertilizers are DAP, 67% MAP, 26% and TSP, 7%. 

Although superphosphate fertilizer provides available phosphorus, it is advantageous to provide other needed elements such as nitrogen and potassium at the same time. Thus, diammonium hydrogen phosphate [(NH4)2HP04] provides both nitrogen and phosphorus, while potassium ammonium phosphate [K(NH4)HP04] makes available the three elements most needed in the maintenance of soil fertility. 

Most of the ammonia that is produced is employed as fertilizer or used to manufacture other fertilizers, such as urea, ammonium sulfate, ammonium nitrate, or diammonium hydrogen phosphate. Ammonia is also used in the Solvay process, and it is a starting material for the manufacture of cyanides and nitriles (which are used to make polymers such as nylon and acrylics) as well as aromatic compounds containing nitrogen, such as pyridine and aniline. 

Diammonium Phosphate (DAP). Ammonium phosphates did not come on the fertilizer scene in significant quantities until the early 1960s however, they have rapidly become the leading form of phosphate fertilizer in the world. Almost all new phosphate fertilizer complexes built in recent years, and those planned, are for the production of ammonium phosphate as the major product. In 1960, world production of ammonium phosphates was equivalent to only 0.5 million mt of P205. By 1990 it was up to 15.4 million mt and by 1999 it has reached 16.7 million mt. Ammonium phosphates now provide two-thirds of total world phosphate fertilization. 

Ammonium phosphates Calcium metaphosphates Defluorinated phosphates Diammonium phosphates Fertilizers, mixed made in plants producing phosphatic fertilizer materials... 

Ammonium Phosphate. Ammonium phosphates have a long history of use as a fertilizer. They are not as easily leached from the soil as ammonium nitrate, but cannot be made in high nitrogen concentrations. There are three forms of ammonium phosphate monoammonium phosphate (MAP, NH4H2P04), diammonium phosphate (DAP, [NH4]2HP04), and triammonium phosphate (TAP, [NH4]3P04). Unfortunately, triammonium phosphate is unstable and loses ammonia easily. Ammonium phosphates are produced by reacting ammonia with phosphoric acid (Reaction 3.8). 

Although ammonium phosphate had long been known to be an effective fertilizer and small quantities had been produced in several countries from time to time, it did not become a popular fertilizer until the 1960s. Ammonium phosphates (diammonium phosphate and monoammonium phosphate) are now the leading form of phosphate fertilizer in the world. 

Several systems have been patented for removal of the unreacted ammonia from the crude product gas. The early Andrussow processes used dilute sulfuric acid ( 6%) as absorbent and produced ammonium sulfate as a by-product. However, the high cost of processing this material has made it increasingly difficult to compete in the already oversupplied fertilizer market. Unless there are special circumstances, present economics and environmental considerations favor the use of a recycle system to recover the unconverted amonia. The typical ammonia recovery systems use monoammonium phosphate at 80°C as the absorbent to react with the unconverted ammonia in the crude product gas to form diammonium phosphate. The diammonium phosphate solution then undergoes a thermal reversal process to liberate ammonia for recycle. The regenerated monoammonium phosphate solution is reused in the absorption system. Polyhydroxyboric acid complex is an alternative absorbent for ammonia recovery that works on the same principles. 

Fig. 2. Fertilizers in the prilled or granular form (a), prilled ammonium nitrate (b), prilled urea (c), granular urea (d), granular diammonium phosphate ...

Chisso-Asahi Fertilizer Company, Ltd. This company utilizes thermoplastic resins, such as polyolefins, poly(vinyhdene chloride), and copolymers, as their coating materials. The coatings are dissolved in fast-drying chlorinated hydrocarbon solvents and are appHed to a variety of substrates including urea, diammonium phosphate [7783-28-0] potassium sulfate [7778-80-3], potassium chloride [7447-40-7], and ammonium nitrate/potassium sulfate-based N—P—K fertilizers. 

Ammonium polyphosphate is one of the most often used phosphoric fertilizers (Corbridge, 1980). It was found to be equally effective when compared with single superphosphate and diammonium phosphate for increasing the yields of wheat and maize and for increasing the available phosphorus content in soil during field experiments (Sharma and Singh, 1998). 

Mono- and diammonium phosphate are used as solid fertilizers, whereas ammonium polyphosphate is mainly utilized in solution as a liquid fertilizer, since unlike the orthophosphates, it is very soluble and is more difficult to granulate than the orthophosphates. As a result of its complexing properties, it also keeps impurities (iron, aluminum, magnesium etc.) in solution. 

Markets. Industrial use of ammonia varies according to region. For example, industrial usage represents 20% of the ammonia production in the United States and Western Europe, 10% in the USSR, 1—10% in Asia, and 5% in Latin America and North Africa (79). Fertiliser ammonia consumed domestically in most countries is converted to straight or compound fertilizers such as urea, ammonium nitrate, diammonium phosphate, and various grades of mixed fertilizers. However, almost 29% of ammonia nitrogen in the United States is consumed as direct application material. The use of nitrogen solution such as urea and ammonium nitrate (UAN) has also become popular in the United States and the USSR. 

---